The funeral directors who dealt with Eileen's death are still in operation, it might be worth sending them an email to see if they can provide any further info, such as a death notice:http://www.fountainsfunerals.co.nz/aboutus.htm

This is the link for the NZ Whitepages online. If you search WORTHINGTON in Auckland, you will find an entry that matches the initials you are after:http://whitepages.co.nz/